TIMEOUT
MAYBE
Trs:
 {g(c(s(x), s(y))) -> f(c(x, y)),
     g(c(x, s(y))) -> g(c(s(x), y)),
  f(c(s(x), s(y))) -> g(c(x, y)),
     f(c(s(x), y)) -> f(c(x, s(y)))}
 Open